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Thu, 3 Dec 2020 03:20:56 +0000 Date: Wed, 2 Dec 2020 19:20:52 -0800 From: Roman Gushchin To: Muchun Song CC: Johannes Weiner , Michal Hocko , Vladimir Davydov , Andrew Morton , Cgroups , Linux Memory Management List , LKML Subject: Re: [External] Re: [PATCH] mm/memcontrol: make the slab calculation consistent Message-ID: <20201203032052.GA1568874@carbon.DHCP.thefacebook.com> References: <20201202121434.75099-1-songmuchun@bytedance.com> <20201202211646.GA1517142@carbon.lan> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Originating-IP: [2620:10d:c090:400::5:5b23] X-ClientProxiedBy: MWHPR07CA0018.namprd07.prod.outlook.com (2603:10b6:300:116::28) To BYAPR15MB4136.namprd15.prod.outlook.com (2603:10b6:a03:96::24) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from carbon.DHCP.thefacebook.com (2620:10d:c090:400::5:5b23) by MWHPR07CA0018.namprd07.prod.outlook.com (2603:10b6:300:116::28) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3632.17 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData: =?us-ascii?Q?Wal68YEdaWBeM8wujAJrhE01M6ZaDbfL2AEvyJQEXDZljgOMOSUtDsDEjq61?= =?us-ascii?Q?jeUNcVdCvC+z0bZvxuvbGMSyrqmqbngQWlSqYG9FM7pRD4TcEmLAlEXu4UbZ?= =?us-ascii?Q?RQd826cWHCRF/Omaf0YdPTJ2Nw179XvMYhZbw+XSmBw0AILUyG7lsQKUXhvN?= =?us-ascii?Q?2LaTh+Z7Ppq4/Tex80zp9aXz3/mX6gRbhUxGroj2YxQbQxKMHIEObopt6FCD?= =?us-ascii?Q?2yKrHax2GVPWfzm05XQycL5jBIePEgR4o/x/1cHqVbu+Hw/geb4CPAV2zQIO?= =?us-ascii?Q?k/Z2uqAfi807BZYi5LNhwnzN5kYHt1LdGx46xOwopkPMcG8HVe8ggq5Mh0PD?= =?us-ascii?Q?wyKpVSLfATKj/twgiXkXQoE0BvZp/YLUqk20QU27i90Aq2PDhmCy15b7I5yo?= =?us-ascii?Q?i9yK7rS4f+mBhBiO/JifRfXkCYNygWMxWq6sGLIfMGbywvfSKuA38/rX0cJ1?= =?us-ascii?Q?1keoK65xZdgl9hussAVEBuGH78NO9Y99sAnKHDCwfRBCmzFgXpXMqIfzPyeh?= =?us-ascii?Q?3B9BHH/Wm12YqCz44VqX+DzO+CX/iPZUi5/BPlwtl0fsDkMHu8yBsdaZDMKY?= =?us-ascii?Q?/kFM6d5r+3/SVSWUCAewpA0Se6Kg09gvYo/pWZUTsv/lDMiLoFwN/OwZt0rT?= =?us-ascii?Q?J+QokVEgwISgbdDLuTNSuwMZQeG4u+ENY7Js2WkQtyKDtoW5DjznkGPcRvoc?= =?us-ascii?Q?hcUk8W5oJKNlVmeLZBiUtLvk/331l5IbtaUCFZA3gGY6z559RVwC8MzJJzcD?= =?us-ascii?Q?5h4HnR7fiG3H4O2k3TnvHtNHnUHwD6UEK+0VsskVCBxjngLFvxcadhCXHAqZ?= =?us-ascii?Q?IlnaHox5Drn1d19kCnlBItdFMB99MBrRRowAJuJADa25uBOxFduQtkdIy+Ld?= =?us-ascii?Q?Q/qTSDoEo7HiHTVZrvJTH/5k9JfNPSoogU+/wWRUN6pRqcZTPZISUm+6YGyL?= =?us-ascii?Q?xU6mhvh+oywZcuUfqmraVUBjMS9ZcFfl8oR69HgnS6UVuHmOKjX3psmugGYA?= =?us-ascii?Q?/WRpDhn5Tn0Irh68NOqn+Rfdgw=3D=3D?= X-MS-Exchange-CrossTenant-Network-Message-Id: 997ccd0b-62fe-4d43-aba6-08d8973a72cf X-MS-Exchange-CrossTenant-AuthSource: BYAPR15MB4136.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Dec 2020 03:20:56.4624 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: VFazO+f6RvKOKM5+pTotgyvN13mI5XOZWB9hg+A98wLITQw2mb3CZWGokd+HgK+y X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB2760 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.312,18.0.737 definitions=2020-12-03_01:2020-11-30,2020-12-03 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 phishscore=0 adultscore=0 clxscore=1015 priorityscore=1501 mlxscore=0 bulkscore=0 lowpriorityscore=0 mlxlogscore=999 malwarescore=0 spamscore=0 suspectscore=1 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2012030018 X-FB-Internal: deliver X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Dec 03, 2020 at 10:53:33AM +0800, Muchun Song wrote: > On Thu, Dec 3, 2020 at 5:16 AM Roman Gushchin wrote: > > > > On Wed, Dec 02, 2020 at 08:14:34PM +0800, Muchun Song wrote: > > > Although the ratio of the slab is one, we also should read the ratio > > > from the related memory_stats instead of hard-coding. And the local > > > variable of size is already the value of slab_unreclaimable. So we > > > do not need to read again. Simplify the code here. > > > > > > Signed-off-by: Muchun Song > > > --- > > > mm/memcontrol.c | 22 +++++++++++++++++----- > > > 1 file changed, 17 insertions(+), 5 deletions(-) > > > > Hi Muchun! > > > > > > > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > > index 9922f1510956..03a9c64560f6 100644 > > > --- a/mm/memcontrol.c > > > +++ b/mm/memcontrol.c > > > @@ -1545,12 +1545,22 @@ static int __init memory_stats_init(void) > > > int i; > > > > > > for (i = 0; i < ARRAY_SIZE(memory_stats); i++) { > > > + switch (memory_stats[i].idx) { > > > #ifdef CONFIG_TRANSPARENT_HUGEPAGE > > > - if (memory_stats[i].idx == NR_ANON_THPS || > > > - memory_stats[i].idx == NR_FILE_THPS || > > > - memory_stats[i].idx == NR_SHMEM_THPS) > > > + case NR_ANON_THPS: > > > + case NR_FILE_THPS: > > > + case NR_SHMEM_THPS: > > > memory_stats[i].ratio = HPAGE_PMD_SIZE; > > > + break; > > > #endif > > > + case NR_SLAB_UNRECLAIMABLE_B: > > > + VM_BUG_ON(i < 1); > > > + VM_BUG_ON(memory_stats[i - 1].idx != NR_SLAB_RECLAIMABLE_B); > > > > Please, convert these to BUILD_BUG_ON(), they don't have to be runtime checks. > > Agree. But here we cannot use BUILD_BUG_ON(). The compiler will > complain about it. We can! We just need to change the condition. All we really need to check is that NR_SLAB_UNRECLAIMABLE_B immediately following NR_SLAB_RECLAIMABLE_B. Something like BUILD_BUG_ON(NR_SLAB_UNRECLAIMABLE_B != NR_SLAB_RECLAIMABLE_B + 1) should work (completely untested). > > > > > > > > + break; > > > + default: > > > + break; > > > + } > > > + > > > VM_BUG_ON(!memory_stats[i].ratio); > > > VM_BUG_ON(memory_stats[i].idx >= MEMCG_NR_STAT); > > > } > > > @@ -1587,8 +1597,10 @@ static char *memory_stat_format(struct mem_cgroup *memcg) > > > seq_buf_printf(&s, "%s %llu\n", memory_stats[i].name, size); > > > > > > > Can you, please, add a small comment here stating that we're printing > > unreclaimable, reclaimable and the sum of both? It will simplify the reading of the code. > > Will do. Thank you!